I would suggest that you go to Super Training. From there, you can see which stats the EVs are invested in. Sometimes, if the Pokemon have happy emoticons, you can get random training bags from them. (Note: If the Pokemon are laying down, go to them and tap on it and it can get a happy emoticon). Just keep on tapping on it and they might get a bag for you. It might be a reset bag, so you can reset the EVs. Once you get a Reset Bag, have your Lucario keep on punching it until it finally works. Then you can go to normal Super Training and train your Lucario in the proper EVs.
If you want to speed up your training, have a Pokemon with maxed out EVs do all of the training in every area (Atk, Sp. Atk, Def, Sp. Def, Speed, HP) until you get up to Training Level 3. They won't gain anymore EVs (Note: You can see if they are maxed out if they have the muscle icon on the upper left of the bottom screen). You can get 12 EVs from training now!
EDIT: Oh yeah, now that you know this, resetting is obviously not the best option.
I hope I helped!